Device and method for alignment of vertically stacked wafers and die

Abstract

A device is provided that includes a first die having a first alignment structure that includes a plurality of first transmission columns arranged in a pattern and a second die positioned on the first die, the second die having a second alignment structure that includes a plurality of second transmission columns arranged in the same pattern as the first transmission columns. The first and second transmission columns are each coplanar with a first surface and a second surface of the first and second die, respectively.

The invention claimed is: 
     
       1. A device, comprising:
 a first wafer having a first surface opposite a second surface; 
 a first alignment structure having: 
 a first discrete base adjacent to the first surface of the first wafer; and
 a first plurality of discrete transmission columns each extending directly from the first discrete base through the first wafer to the second surface and each exposed from the second surface, the first plurality of discrete transmission columns including a first discrete transmission column and a second discrete transmission column, the first discrete transmission column and the second discrete transmission column being electrically connected to one another through the first discrete base; and 
 
 a second alignment structure spaced apart from the first alignment structure, the second alignment structure having:
 a second discrete base adjacent to the first surface of the first wafer, the second discrete base being spaced apart from the first discrete base; and 
 a second plurality of discrete transmission columns extending from the second discrete base through the first wafer to the second surface, the second plurality of discrete transmission columns including a third discrete transmission column and a fourth discrete transmission column, the third discrete transmission column and the fourth discrete transmission column being electrically connected to one another through the second discrete base. 
 
 
     
     
       2. The device of  claim 1  wherein a surface of ends of the transmission columns is coplanar with the second surface. 
     
     
       3. The device of  claim 1  wherein the transmission columns are electrically conductive. 
     
     
       4. The device of  claim 1 , further comprising:
 a second wafer on the first wafer, the second wafer having a first surface opposite a second surface; and 
 a third alignment structure having a third discrete base adjacent to the first surface of the second wafer, the third alignment structure including a third plurality of transmission columns extending from the third discrete base of the third alignment structure through the second wafer to the second surface of the second wafer. 
 
     
     
       5. The device of  claim 4  wherein the third alignment structure and the first alignment structure are aligned. 
     
     
       6. The device of  claim 4  wherein the transmission columns of the first alignment structure are aligned with respective ones of the transmission columns of the third alignment structure. 
     
     
       7. A semiconductor wafer, comprising:
 a first surface and a second surface opposite to the first surface; 
 a first conductive pad adjacent to a kerf area of the first surface; and 
 a plurality of conductive columns each in the kerf area and including a first end and a second end, the first end directly contacting the first conductive pad, and the second end being a part of the second surface, the plurality of conductive columns arranged in a pattern, 
 wherein an end surface of the second end of a conductive column of the plurality of conductive columns is exposed from the second surface. 
 
     
     
       8. The semiconductor wafer of  claim 7 , wherein the first conductive pad is of a non-rectangular shape. 
     
     
       9. The semiconductor wafer of  claim 7 , wherein the first conductive pad and the plurality of conductive columns are of a same material. 
     
     
       10. The semiconductor wafer of  claim 7 , wherein a surface of the first conductive pad protrudes beyond the first surface. 
     
     
       11. The semiconductor wafer of  claim 7 , wherein the plurality of conductive columns includes a first conductive column, a second conductive column and a third conductive column, the first conductive column and the second conductive column arranged in a first direction, and the first conductive column and the third conductive column arranged in a second direction that crosses the first direction. 
     
     
       12. The semiconductor wafer of  claim 7 , wherein the plurality of conductive columns are arranged in a two dimensional pattern.